Not all plants are the same –plant choice and potential for air quality improvement

Dr Tijana Blanuša

Principal Horticultural Scientist, RHS

tijanablanusa@rhs.org.uk

Vegetation can help – but the extent of cover and

choice of species are important!!

Environmental and well-being issues in cities….

Cameron and Blanusa, 2016, Annals of Botanyhttp://aob.oxfordjournals.org/content/early/2016/07/19/aob.mcw129.abstract

• Excess heat

• Localised flooding

• Aerial pollution

• Noise

• …

Extent of maintenance …

Leaf morphology and particle pollution capture

Blanusa et al. (2015), Urban Forestry and Urban Greening, 1095-1101

Species differ!

Species

Cotoneaster

Crataegus

Ligustrum 'A

ureum'

'Red Robin'Taxus

Lea

f P

b c

on

cen

tra

tion

(mg

kg

-1)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Before exposureAfter 8 dry days in situ

• 3-fold increase in concentration in Cotoneaster, almost 3-fold in Crataegus

• 2-fold increase in Ligustrum and Taxus• < 2-fold increase in Photinia ‘Red Robin’

Leaf Pb concentration, hedge plants, 8 day roadside exposure, Summer 2016

Blanusa, ongoing project, unpublished

Cotoneaster – control and street-level capture of particles

Control Exposed to street-level pollution for 7 days

Blanusa, ongoing project, unpublished

What can plants do for us indoors?

- Air quality improvement (VOCs, CO2, particulate matter removal)

- Increase in RH

- Well being / productivity increase

Net assimilation at 261 mol m-2s-1 (n = 8)

Species / cultivar

Dracaena 'Lemon lime'

Dracaena 'Golden coast'

Spathiphyllum 'B

ellini'

Spathiphyllum 'V

erdi'

Zamioculcas

Ne

t C

O2 a

ssim

ilatio

n (m

ol m

-2s-1

)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Does indoor plant choice matter?

C. Gubb, PhD project, unpublishedUniversity of Reading

Likely – yes

but

Environmental conditions need to be considered (light, substrate and air

moisture, substrate health)

Watch this space !

What does this mean for practice?

• Planners, architects, builders

‘anything, everything, a tree’(L. Hunt )

• Landscapers, horticultural specialistsConsider environmental impact of the plants, and which plant traits would be

useful to improve the delivery of environmental benefits (cooling, noise, pollutant trapping, rainwater capture…)

Perennial, physiologically active plants, with high ETp(strong ‘pumps’), light, rough/hairy foliage

https://www.rhs.org.uk/communities/pdf/Greener-Streets/rhs-front-garden-guide